Photographic silver halide emulsions containing nitrosubstituted or unisubstituted cinnamic acid or cinnamaldehyde

ABSTRACT

A LIGHT-SENSITIVE SILVER HALIDE MATERIAL HAVING THEREON A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER AND CONTAINING, IN THE LIGHT-SENSITIVE SILVER HALIDE LAYER OR IN A LAYER IN CONTACT THEREWITH, AS AN ANTIFOGGANT AND STABILIZER A COMPOUND HAVING THE FORMULA:   ((NO2)(N-1)-PHENYL)-CH=CH-R   WHERE R IS EITHER   -COOH OR -CO-H   AND N IS 1 OR 2.

United States Patent 3,573,915 PHOTOGRAPHIC SILVER HALIDE EMULSIONSCONTAINING NITRO-SUBSTITUTED OR UN- SUBSTITUTED ClNNAMIC ACID 0RCINNAMAL- DEHYDE Giacomo Luciani and Fritz Dersch, Binghamton, N.Y.,assignors to GAF Corporation, New York, N.Y. No Drawing. Filed Nov. 16,1966, Ser. No. 594,675 Int. Cl. G03c N34, N06, 1/76 US. CI. 9667 ClaimsABSTRACT OF THE DISCLOSURE A light-sensitive silver halide materialhaving thereon a light-sensitive silver halide emulsion layer andcontaining, in the light-sensitive silver halide layer or in a layer incontact therewith, as an antifoggant and stabilizer a compound havingthe formula:

OH=CHR where R is either This invention relates in general tophotography and in particular to the provision of novel antifogging andstabilizing compounds for use in connection with the preparation and/orprocessing of photographic silver halide emulsions.

It is well known that light-sensitive materials such as gelatin silverhalide emulsion exhibit a marked tendency to fog. The term fog as usedin the photographic art connotes that portion of the density obtainedupon development which arises by virtue of factors other than thephotographic exposure. The fog may be attributable to a number ofinfluences including, for example, excessive ripening of the emulsion,prolonged storage of the film and especially under conditions ofelevated temperature and/or humidity, as well as by prolongeddevelopment of the exposed emulsion, etc.

Resort to rapid-developing operations which usually require the use ofelevated temperatures likewise presents severe problems of fog.

As is well known, it is conventional practice in the photographic art toincorporate into silver halide emulsions various types of sensitizingagents in order to enhance their sensitometric response. For example,gold or sulphur sensitizing agents or combinations of both have beenextensively employed for such purposes. Invariably, however, priorattempts to achieve ultimate speed in photographic emulsions sosensitized have been to a large extent vitiated by the concomitantoccurrence of fog.

Furthermore, similar fogging problems are encountered when employingsensitizers of the reduction type, such sensitizing agents usually beingemployed to augment the sensitizing properties of gold, sulphur and thelike. As examples of compounds known to function as reductionsensitizers in silver halide emulsions there may be mentioned inparticular the following: imina-amino-methanesulfinates; hydrazine andhydrazine derivatives; certain amines such as diethylenetn'amine,triethylenetetrarnine, triethanolamine, silene compounds having asilicon-hydrogen bond, spermine, sodium formaldehyde sulfoxolate,stannous chloride, alkali metal sulfite; sugars, such as lactose,dextrose, ascorbic acid and the like. However, like many of theirpredecessors, the use of the afore- "ice mentioned compounds haslikewise been encumbered by severe fogging problems and especially whenemployed in the preparation of photographic silver halide emulsions ofthe high-speed type.

The foregoing problems have in many instances necessitated resort to theuse of antifoggant compounds such as benzotriazole, nitro-benzimidazole,phenylmercaptotetrazole and the like. However, these particularcompounds have been ascertained to provide somewhat suboptimum resultssince, while serving as effective antifoggants, they display apronounced tendency to reduce emulsion speed. To a great extent, thedepression on emulsion sensitivity has more than offset any possiblebenefits arising from their use.

Considerable investigation likewise indicates that the gelatin itselfmay be a source of fogging problems. Quite obviously, the use ofgelatins which are not properly balanced with regard to their content ofsensitizing, restraining and antifogging substances frustrates attemptsto alleviate the fogging problem. Despite the fact that themanufacturers of photographic gelatins are, for the most part, highlyskilled in controlling the proper content of sensitizers, antifoggants,etc., e.g., by careful selection and treatment of raw materials, bonesand hides, as well as the careful control of the acid or alkalinetreatment of the extraction of gelatin, and selection of filter aids, itis nevertheless frequently experienced that the gelatin material remainsa causal factor with regard to fog. While the substantial majority ofcommercial gelatins have been ascertained to be offensive in thisregard, the fogging problem has been found to be highly manifest withpigskin, chicken feet and rabbit skin type gelatins and especially whenutilized in the preparation of emulsions of the ammonia type.

Photographic silver halide emulsions are usually provided with one ormore speed-increasing agents, e.g., the polyoxyalkylenes and derivativesthereof for purposes of compensating for the depression in sensitometricresponse caused by the antifoggant. However, the net result has oftenbeen a re-establishment of the fogging problem.

The fogging problem is also aggravated by the use of hardening agentsfor the photographic emulsion, e.g., formaldehyde, glyoxal, etc.

In accordance with the discovery forming the basis of the presentinvention, it has been found that the antifogging and stabilizationcharacteristics of light-sensitive silver halide emulsions can besynergistically modified to advantage by the utilization of a particularclass of chemical compounds in connection with the preparation and/orprocessing of such emulsions.

Thus, a primary object of the present invention resides in the provisionof improved antifogging and stabilizer compounds in which the foregoingand related disad' vantages are eliminated or at least mitigated to asubstantial degree.

Another object of the present invention resides in the provision oflight-sensitive silver halide emulsions containing a compound whichstabilizes the emulsion against fogging while exhibiting little, if any,tendency to reduce the speed or contrast of such emulsions.

A further object of the present invention resides in the provision oflight-sensitive silver halide emulsions and photographic elementsprepared therewith containing an antifogging compound which issubstantially devoid of any tendency to reduce the sensitivity of theemulsion to light of longer wave length due to the presence of one ormore sensitizing dyes.

A still further object of the present invention resides in the provisionof a process for the treatment of an exposed photographic silver halideemulsion wherein at least one of the steps of pretreating or developingthe (NOz) n-l wherein R is selected from the group consisting of -(HJOHand H and wherein n represents 1 or 2.

The compounds included by the above depicted structural formula may'besummarized as follows:

o-Nitrocinnamaldehyde m-Nitrocinnanialdehyde CH=CH CHOp-Nitrocinnamaldehyde o-Nitrocinnamic acid CH=CHC O OH p-Nitrocinnamicacid 11102 m-Nitrocinnamic acid C|1H=C H O H O einnamic aldehyde H= C H-O O O H einnamic acid The novel stabilizer compounds of the presentinvention can be prepared according to well known techniques. Forexample, the preparation of the nitro-cinnamic acids is described inBellstein, vol. 9, pp. 604-606; the preparation of the nitrocinnamaldehydes is described in Organic Synthesis, vol. 33, p. 60.

Improved fog reduction and other beneficial effects are obtained whenthe aforementioned compounds are incorporated into the silver halideemulsion as ripening finals or as coating finals. As is well known,ripening finals are added during the ripening or sensitivity increasingstage of the emulsion making process. Such additions may be eifectedbefore, during or after the decomposition of the soluble silver saltsuch as silver nitrate by means of a soluble halide such as potassiumbromide, sodium chloride or the like in the presence of a suitablecolloid carrier such as gelatin, polyvinyl alcohol, solubilized caseinalbumen or the like.

Coating finals are added to the emulsion just prior to coating on asuitable support such as glass, paper or film at the time when theemulsion has nearly attained its maximum sensitivity.

It will also be understood that the novel stabilizers of the presentinvention may be incorporated in a layer adjacent to the sensitizedlayer such as an anti-abrasion layer. The stabilizing compound may beutilized in concentrations varying over a relatively wide range; forexample, when added to the light sensitive silver halide emulsion layeras a ripening final, it is found that optimum realization of resultsprovided herein are assured with stabilizer concentrations ranging fromas low as 25 milligrams up to about 500 milligrams per 1 mole of silverhalide. The concentration selected Within the aforestated range willdepend to a large extent on the type of emulsion employed and thus, itis advisable to determine the optimum concentration from case to case.If added during the emulsion preparation state, stabilizerconcentrations ranging from 2 to 500 milligrams per 1 mole of silverhalide are found to be quite suitable.

The stabilizer compounds contemplated herein can be applied in a varietyof ways to impart stability to photographic elements. As previouslymentioned, they may be included as a constituent of the emulsion layer,of a surface layer over the emulsion or alternatively, over the base orsupport.

Further embodiments of the present invention contemplate the addition ofsuch compounds to at least one of the developing, fixing, washing,drying, etc., solutions utilized in the processing of the exposedemulsion.

In general, it is found that the improvements provided by the presentinvention are particularly manifest according to procedures wherebydevelopment is effected in the presence of said stabilizer compounds.This, of course, would be the case should the stabilizer be included inthe light-sensitive photographic element, the developing solution and/orsuitable developer pre-bath. In any event, when incorporated into thephotographic developer or other processing bath, the stabilizers of thepresent invention are preferably employed in concentrations ranging fromabout 10 to about 500 milligrams per liter of solution, with a range ofabout 20 milligrams to about 200 milligrams per liter being particularlypreferred.

In addition to being useful in orthochromatic and panchromaticemulsions, the stabilizers may also be used in nonsensitized emulsions,X-ray emulsions, paper emulsions, color emulsions and the like. If usedwith sensitizing dyes, they may be added to the emulsion before or afterdye addition. Moreover, the present stabilizers may also be employed inconjunction with other known antifoggants and stabilizers, reduction orsulfur sensitizers, metal and noble metal sensitizers or in combinationwith other additive agents and the like.

The stabilizer may also be employed in gelatin or other water-permeablecolloids including polyamides or a mixture of gelatin with a polyamideas described in U.S.

Patent No. 2,289,775; polyvinyl alcohol and gelling compound asdescribed in US. Patent No. 2,249,537; polyvinyl acetaldehyde acetalresins and partially hydrolyzed acetate resins described in US. PatentNos. 1,939,422 and 2,03 6,092; cellulose derivatives, e.g., cellulosenitrate, cellulose acetate, and the lower fatty acid esters of celluloseincluding sample and mixed esters and ethers of cellulose and the like.

When preparing the photographic emulsion in accordance with the presentinvention, a solution of the stabilizer in a suitable solvent, such aswater, alcohol, dimethyl formamide, N-methyl-Z-pyrrolidone, oralcohol-water mixture adjusted to a neutral or slightly alkaline pH,i.e., about 6 to 8 is made up and the solution mixed with the emulsionat any convenient stage during its preparation, but preferably duringripening or just prior to coating.

The following examples are given for purposes of illustrating thepresent invention in greater detail, and are not to be considered in anyway as being limitative thereof.

EXAMPLE I A high speed negative ammonia emulsion was prepared using theformula described on page 332, Photographic Chemistry, vol. 1, by PierreGlafkides (1958). A pigskin gelatin was used. This emulsion was called(a). A second emulsion (b) was prepared which differed from emulsion (a)in that we used, in the second ripening (after washing) 1 cc. of asolution of o-nitro-cinnamaldehyde in N-methyl-Z-pyrrolidone.

Those emulsions were then readied for coating on film base, that is,melted at 40 C., necessary coating finals were added, such asstabilizers and hardeners. Emulsion samples were coated on a suitablecellulose ester base and dried. Samples of these film coatings were thenexposed in a Type IB Sensitorneter and developed in a developer of thefollowing composition:

Water to make 1 liter.

The sensitometric results were as follows:

Relative Fog 12 speed developer Emulsion:

EXAMPLE II Example II differs from Example I in that the pigskin gelatinwas replaced with an inert bone gelatin. There was added to the secondripening (after washing), a gold thiocyanate solution, which wasprepared according to Glafkides (see Example I), page 319. There wasalso added a solution 1:10,000 of Na S O as a sulfur sensitizer(Glafkides, p. 284) and a solution of hydrazine as a reductionsensitizer. The pH and pAg was adjusted by adding dilute sulfuric acidand KBr solution. Since the optimum amounts of these solutions depend onthe selection of the gelatin, they have to be determined from case tocase by fractional experiments (see Statistical Methods for Chemists byW. J. Youden, 1951, pp. 106-115). The so-prepared emulsion is called(a). Emulsion (b) differed from emulsion (a) in that we used 2 cc. of a5% solution of p-nitrocinnamic acid in the after ripening per 1 kg.emulsion. The results were:

6 EXAMPLE 111 Example III differs from Example II in thatp-nitrocinnamic acid was replaced by m-nitrocinnamic acid.

EXAMPLE IV Example IV was conducted similarly to Example II. However,the reduction sensitizer hydrazine was replaced by a solution 1:l0,000of stannous chloride, while in emulsion (b) the p-nitrocinnamic acid wasreplaced with onitrocinnamaldehyde.

EXAMPLE V Example I was repeated except that the pigskin gelatinemployed in emulsion sample (b) received a pre-treatment as follows:

To 1 liter of a 10% solution of pigskin gelatin at 40 C. there wereadded 24 cc. of a 5% solution of o-nitrocinnamaldehyde. After thisaddition, the so-prepared gelatin solution is chilled and dried andground. The results were:

Relative Fog 12 speed developer Emulsion:

EXAMPLE VI Example VI is similar to Example II; however, the N S Oemployed in emulsion sample (a) was replaced by thioacetamide. 1 cc.thioacetamide 1:10,000 can take the place of 20 cc. Na S O 1:10,000.Emulsion sample (b) is like (a) but contains in addition,o-nitrocinnamaldehyde. The results are similar to those in Example II.

EXAMPLE VII Example VII is similar to Example VI, but, instead ofthioacetamide, diethyldithiocarbamic acid was used with almost identicalresults.

EXAMPLE VIII Relative Fog 12 speed developer Emulsion:

EXAMPLE IX A high speed negative ammonia emulsion was prepared using theformula described on p. 332, Photographic Chemistry, vol. 1 by PierreGlafkides (1958). A pigskin gelatin was used. This emulsion was called(a). A second emulsion (b) was prepared which differed from emulsion (a)in that there was used, in the second ripening (after washing) 2 cc. ofa 5% solution of cinnamaldehyde in ethanol. These emulsions were thenreadied for coating on film base, that is melted at 40 C., necessarycoating finals were added, such as stabilizers and hardeners. Emulsionsamples were coated on a suitable cellulose ester base and dried.Samples of these film coatings were then exposed in a Type IBSensitometer and developed in a developer of the following composition:

Water to make 1 liter.

The sensitometric results were as follows:

Relative Fog 12 speed developer Emulsion:

EXAMPLE X Example X differs from Example IX in that the pigskin gelatinwas replaced with an inert bone gelatin. To the second ripening (afterwashing) was added a gold thiocyanate solution, which was preparedaccording to Glafkides (see Example I) p. 319. There was also added asolution l:10,000 of Na S O as a sulfur sensitizer (Glafkides p. 284)and a solution of hydrazine as a reduction sensitizer. The pH and pAgwas adjusted by adding dilute sulfuric acid and KBr solution. Theso-prepared emulsion is called (a). Emulsion (b) differed from emulsion(a) in that there was used 2 cc. of a 5% solution of cinnamaldehyde inthe after ripening per 1 kg. emulsion. The results were:

Relative Fog 12 speed developer Emulsion:

EXAMPLE XI Example XI was conducted similarly to Example X. However, thereduction sensitizer hydrazine was replaced by a solution 1210,000 ofstannous chloride.

EXAMPLE XII Example XII was conducted similarly to Example X with theexception of using in place of the hydrazine solution 1:10,000 a 5%solution of sodium sulfite. The results were almost identical to thosein Example X.

EXAMPLE XIH EXAMPLE XIV Example I is repeated except that the pigskingelatin employed in the preparation of emulsion sample (b) is subjectedto the following pre-treatment:

To 1 liter of a solution of pigskin gelatin at 40 C. there was added 24cc. of a 5% solution of cinnamaldehyde. After this addition, theso-prepared gelatin solution is chilled and dried and ground. Theresults were:

Relative Fog 12 speed developer Emulsion:

8 EXAMPLE XV Example XV is similar to Example II; however, the Na S Oemployed in emulsion sample (a) was replaced with thioacetamide. 1 cc.thioacetamide 1:10,000 can take the place of 2 0 cc. Na S O 1: 10,000.Sample (b) is like (a) but contains in addition, cinnamaldehyde. Theresults are like those in Example II.

EXAMPLE XVI Example XVI is similar to Example XV, but instead ofthioacetamide, diethyldithiocarbamic acid was used with almost identicalresults.

EXAMPLE XVII Example XVII is like Example XIII except that thepolyethylene glycol was replaced by 10 cc. of a 1% solution ofdiethylene triamine.

EXAMPLE XVIII Example XVIII is like Example XVII except that thediethylene triamine was replaced by triethanol amine.

EXAMPLE XIX The photographic silver halide emulsion described in ExampleII, was readied for coating on a suitable base, finals were added, suchas stabilizers, coating aids, e.g., certain surfactants and as ahardener Was added glyoxal in the amount of 40 cc. of a 5% solution per0.6 mole silver halide. This emulsion is called (a). A similar emulsion(b) was coated but there was added 10 cc. of a /2% solution ofcinnamaldehyde. The results were as follows:

Relative Fog 12 speed developer Emulsion:

EXAMPLE XX Example XX is similar to Example XIX. However, formaldehydewas used in place of glyoxal. The results were almost identical to thosedescribed in Example XIX.

The present invention has been disclosed with respect to certainpreferred embodiments thereof, and there will become obvious to personsskilled in the art various modifications, equivalents or variationsthereof which are intended to be included within the spirit and scope ofthis invention.

What is claimed is:

1. A light-sensitive silver halide emulsion containing as an antifoggantand stabilizer a compound of the following structural formula:

(N O 2) n1 wherein R is selected from the group consisting of 6. Alight-sensitive silver halide emulsion according to claim 1 wherein saidantifoggant and stabilizer compound comprises m-nitrocinnarnaldehyde.

7. A light-sensitive silver halide emulsion according to claim 1 whereinsaid antifoggant "and stabilizer compound comprisesp-nitrocinnamaldehyde.

8. A light-sensitive silver halide emulsion according to claim 1 whereinsaid antifoggant and stabilizer compound comprises cinnamaldehyde.

9. A light-sensitive silver halide emulsion according to claim 1 whereinsaid antifoggant and stabilizer compound comprises cinnamic acid.

10. A light-sensitive photographic element comprising a base and alight-sensitive silver halide emulsion, said light-sensitive silverhalide emulsion containing as an antifoggant and stabilizer a compoundof the following structural formula:

10 wherein R is selected from the group consisting of i ooH 5 and i CH10 and wherein n represents 1 or 2.

References Cited Chem. Absts., vol. 57, 335b.

15 NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant ExaminerUS. 01. X.R. 20 96-95, 66.5, 109

